Mechanical handling truck



May 13, 1952 R. WARD ETAL 2,596,747

MECHANICAL HANDLING TRUCK Filed March 13, 1950 1 F/G./. F/GZ.

Inventors: 05m 7 MRO Jo/wv 2/040 y MMMJM MM Attorneys Patented May 13, 1952 MECHANICAL HANDLING-TRUCK Robert Ward and John Ridl'ey',

Birmingham, England r Application-March 13, 195ii,.Serial No. 149,296

In Great Britain September 27, 1949 4 Claims. 1

This invention has reference to a mechanical handling truck of the kind provided with a lift ing and lowering carriage which carries load supporting brackets or forks each in the form of an approximately L-shaped structure, the horizontal legs of the forks forming a load supporting platform and the vertical legs being suspended on the carriage. In practice, the toes or tips of the platform legs are inserted beneath the load, the load is moved on to the platform legs, the carriage is elevated and the truck conveys the load to a desired position when the operations are reversed.

These platform forks are ordinarily made as high carbon steel castings and are required to carry loads say up to five tons. Each casting is necessarily a robust and weighty structure and does not admit of being handled and manoeuvred by a single person during the stages of casting, machining and fitting.- Apart from this, there is, however, a serious disadvantage that such cast steel forks often possess hidden flaws which remain undiscovered during test but which become apparent under dead or shock load or after a period of service. In this event, the fork or forks fracture and the load falls resulting in injury or loss of life to the truck driver or persons in the vicinity of the falling load apart from damage to the latter and consequent loss of time and inconvenience.

The object of the present invention is to provide a platform fork or bracket for a mechanical handling truck which is stronger yet lighter than those now in use.

A platform fork of the kind referred to and according to the present invention consists of a high carbon steel fabricated structure welded into a channel section having the heel part of the fork reinforced by a block interposed between and welded to the flanges of the channel the web of which forms the load supporting surface.

After fabrication, the usual heat treatment is carried out to restore the toughening properties of the steel.

In the accompanying drawings, a typical example of steel fabricated forks together with a practical application thereof is illustrated:

Fig. l is a, side elevation partly in section of a fork and Fig. 2 is a section taken on the dotted lines l-| to a larger scale.

Fig. 3 is a large scale section taken on the dotted line 2-2 of Fig. 1.

Fig. 4 is a perspective view of a pair of forks constructed according to Figs. 1 and 2, mounted on the carriage of a mechanical handling truck.

Fig. 5 is a section similar to that of Fig. 2 of a modification.

Fig. 6 is a sectional detail of head of the fork.

In the drawings and referring to Figs. 1 to 4, the L-shaped platform fork consists of a web I and three flanges 2 set at right angles and Welded to the web at 3 thus to form two virtually integral channel sections indicated at 4. The flanges 2 of the vertical member 5 of the fork are bored laterally at 6 to receive a round bar section 1 which is bored axially into a sleeved boss 8 thus to enable the fork to be suspended by its boss on a bar 9 of a lifting and lowering carriage 19 mounted on pillars ll of a mechanical handling truck (not shown). The heel part l2 at least of the double channel section fork is reinforced by blocks l3 interposed between and welded at M to the flanges 2 and web I thus to form box sections and to stiffen up and toughen the structure and add resistance to shock and dead loads.

Forks so constructed are made of high-carbon steel plate such as 2" x %"--4560% carbon and after fabrication is complete they are heat treated as by normalising at 400 C., toughened at 800 C., and quenched in oil. As will be seen from Fig. 4, thepweb l of a pair of suspended forks combine to form a platform for the load, the multiple channel structure with theblocked heel l2, l3 operating to resist deflection or shear stresses either under dead or shock loads or inr creased loads resulting from the up or down motion of the'carriage.

In Figs."5 and 6, a high-carbon steel welded fork is shown as a single channel with a block l3 reinforcing the heel l2; this single channel structure is intended for use in cases where lighter loads, say substantially less than five tons, are to be dealt with. In Fig. 6 there is shown a modified construction of a fork-head consisting of a hook l5 for suspension on the bar 9, a bolt It being provided to resist inadvertent upward displacement of the hook.

Advantages flowing from the invention are that the steel fabricated fork is relatively lighter by weight than a cast steel fork designed to carry an equal load, is much cheaper to produce, possesses a greater factor of safety and all risks of casting flaws are avoided.

What we claim is: i

1. An L-shaped lift-truck fork comprising a steel fabricated structure consisting of L-shaped a modified pivoted high carbon steel plates welded into a channel section, the web of the section forming the load supporting surface, and a block interposed between and welded to the channel section at the heel part of the fork.

2. An L-shaped lift-truck fork comprising an L-shaped web, L-shaped plates welded at longitudinal edges thereof to a surface of the web and combining to form channel sections, the web of the structure forming the load supporting surface, and blocks interposed between and welded to the heel part or the channel sections.

3. An L-shaped lift-truck fork according to claim 1, and including a sleeve welded into coaxial holes formed in the flanges ofthe channel section at the upper end of the fork.

4. An L-shaped lift-truck fork according to claim 2, and including a. sleeve welded into oo- 4 axial holes formed through the flanges 01 the channel sections at the upper end of the fork.

ROBERT WARD. JOHN RIDLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

